Rod section of a ground drilling rod, drive element, rod section system, and ground drilling device

ABSTRACT

The invention relates to a rod section of a ground drilling rod, wherein the rod section is configured at the end side to form at least one plug connection and has at one end (a) a male connector with an outer contour or (b) a female connector with an inner contour, wherein, in cross section, the outer contour or the inner contour has a shape deviating from a circle.

The invention relates to a rod section of a ground drilling rod, to adrive element for driving a ground drilling rod into the ground, to arod section system and to a ground drilling device.

In the case of rod-based drilling in the ground, in particular for theproduction of so-called horizontal bores, which can run substantiallyparallel to or at a relatively small angle of inclination to the groundsurface, a drill head is propelled by means of a drilling rod by a drivedevice arranged on the ground surface or in a construction pit. Thedrilling rods used in this case usually consist of individual,interconnected rod sections, which—according to the drilling path—aregradually attached to the rear end of the drilling rod that has alreadybeen drilled and connected thereto.

Different configurations are known for connecting the rod sections orlinks of the drill string to one another. The rod sections can beconnected by means of a threaded connection and/or a plug connection.

For example, it is known from DE 10 2011 010 958 A1 to specify apossibility for connecting two rod sections of a drilling rod whichcombines the advantages of the threaded connections known from the priorart and the axial plug connections. A plug connection is describedwhich—similar to a threaded connection—is based on helicalprojections/grooves running on a threaded male connector with a circularcross section or in a corresponding threaded female connector, theprojections/grooves being designed so that the self-lockingcharacteristic of a threaded connection does not occur.

It has been found that previous connections of the rod sections, despitethe advantages achieved by the corresponding connection, are too complexin design, are difficult to construct or manufacture, cannot be used forall types of ground drilling, and/or are too complex to handle.

The invention was based on the object of specifying an improvedpossibility for connecting two drill string links of a drill string forground drilling, which in particular allows for a simpler configurationin the construction or manufacture and/or a safe and/or simpleconnection.

This object is achieved by the subject matter of the independent claims.Advantageous embodiments are the subject matter of the correspondingdependent claims and/or emerge from the following description of theinvention.

The invention is based on the idea of specifying a way of connecting twodrill string links of a drill string, which allows plugging and uses ashape deviating from the circular shape with regard to thecross-sectional contour (a contour transverse to the longitudinal axisof the drill string link). By means of the deviation from the circularshape, drill string links can be plugged into one another in such a waythat a non-rotatable connection around the longitudinal axis of therespective drill string links, in particular in both directions ofrotation, can be made possible. This allows the drilling rod to beturned both clockwise and counter-clockwise. For example, so-called“paddling” is possible, i.e. a ground drilling operation in which thedrill head can be rotated back and forth about the longitudinal axis ofthe drill string in a specific, controlled angular range. The rotationof the drill head back and forth in the specified angular range canresult in a higher propulsion speed during this “paddling” compared to apurely static thrust of a drill head, which is held at a predeterminedrotational position (roll angle or “time”). There is the possibilitythat, in the case of an inexpensive production for the formation of acontour for one of the plug-in links, a simple possibility is created torotate the drill string in both directions of rotation. Furthermore, aquick connection of the drill string links can be achieved through theplug connection, in which the drill string links do not have to performa large movement about the longitudinal axis of each drill string link.In addition, a non-rotatable, unambiguous connection can be madepossible in which the position of the drill head can be determined interms of an angular position, i.e. the roll angle or the “time” in whichthe drill head is located, since the connected rod sections cannotrotate relative to one another. For example, an expensive, otherwisenecessary transmitter for determining the angular position of the drillhead can be omitted and, if necessary, an inexpensive transmitter can beused, by means of which only a depth determination of the drill head inthe ground can be used. By means of the shape of the plug connection orthe contour that deviates from the circular shape, a rotary assignmentof the angular position of the drill head is possible depending on theposition of the contour of the last rod section of the drill stringvisible to the operator, which can correspond to the position of thecontour of the drive element. The angular position of the rod sectioncan be easily read by means of one or more markings on the rod section,which can preferably be attached to the outside of the rod section,particularly preferably distributed over the circumference and inparticular at the end side. The user can obtain additional benefits froma plug connection that can be easily planned, constructed and/orproduced for a rod section, in that a connection between the rodsections that is easy to handle for the purposes of the application canbe made possible.

The invention creates a rod section of a ground drilling rod, whereinthe rod section is configured at the end side to form at least one plugconnection. At one end, the rod section has (a) a male connector with anouter contour or (b) a female connector with an inner contour. In crosssection, the outer contour or the inner contour has a shape deviatingfrom a circle.

If it is described that a male connector or a female connector isprovided at one end of the rod section, it can be provided that a maleconnector is present at one end of the rod section and a femaleconnector is present at the other end. It is possible to form a plugconnection at both ends of one and the same rod section, wherein, incross section, the outer contour or the inner contour have a shapedeviating from a circle. However, it is also possible that a rod sectionaccording to the invention has an aforementioned male connector with anouter contour or a previously described female connector with an outercontour only at one end, the other end being able to be configured asdesired. A configuration of a rod section in which only one end has amale connector or a female connector with a contour as described allowsthe configuration that it is possible to switch to a differentconnection system.

The term “rod section” in the context of the description comprises anelement which extends along a longitudinal axis and which is part of theground drilling rod or a drill string for ground drilling. The rodsection can be designed as an element with an assigned function(transmitter housing or the like, for example for a transmitter to allowthe depth of the drill head to be determined), which element is arrangedon the front side in the ground drilling rod or drill string, or can bedesigned as an (only mechanical) element extending the ground drillingrod or the drill string as a rod section. The rod section can comprisemechanical channels, for example for drilling fluid, electrical lines,electrical elements and/or electronic elements, which can preferably bearranged in its interior. The rod section can also be designed as an“ground drilling tool,” which can be a drill head arranged at thefront-side end of the drill string. The drill head can be a drill headwith moving parts. However, it can also be provided that the grounddrilling tool has an immovable or rigid or largely immovable or rigidouter contour.

In a preferred embodiment, a rod section within the context of thedescription can have an outer diameter of 25 mm to 65 mm, preferably 30mm to 60 mm, preferably 35 mm to 55 mm, preferably 40 mm to 50 mm. In apreferred embodiment, a rod section within the context of thedescription can have an overall length of 450 mm to 650 mm, preferably500 mm to 600 mm, preferably 520 mm to 580 mm. In a preferredembodiment, a rod section within the context of the description can havea useful length which, in particular, takes into account the length ofthe female connector and male connector. The useful length can resultfrom the total length reduced by the length of the connecting element orelements and can be 400 mm to 600 mm, preferably 450 mm to 550 mm,preferably 475 mm to 525 mm. In a preferred embodiment, a rod sectionwithin the context of the description can have a groove for engaging anengaging element for moving the drill string, for example a (locking)pawl, which can have an outer diameter of 15 mm to 55 mm, preferably 20mm to 50 mm, preferably 25 mm to 45 mm, preferably 30 mm to 40 mm. In aparticularly preferred embodiment, the total length of the rod sectioncan be 550 mm and the outer diameter of the rod section can be 45 mm. Ina particularly preferred embodiment, the useful length of the rodsection can be 500 mm. In a particularly preferred embodiment, the outerdiameter of a groove for engaging an engaging element for moving thedrill string can have an outer diameter of 35 mm. The stated values forthe outside diameter of the rod section, the (total) length of the rodsection, the useful length of the rod section and the outside diameterof a groove on the rod section are not restrictive values; inparticular, the size of the construction pit or the shaft for thearrangement of the auger device and/or the nature of the ground can beadapted in order to carry out a ground drilling operation efficiently.

In the context of the description, the term “ground drilling rod” ordrill string comprises a string which has a ground drilling tool and arod and which can be moved by means of a ground drilling device or adrive device in order to drill a borehole through the ground.

The term “ground drilling device” in the context of the descriptioncomprises any device that can move a drill string with rod sections inan existing channel or in a channel to be created in the ground in orderto create or widen a bore, in particular a horizontal bore, or to drivepipes or other elongate bodies into the ground. The ground drillingdevice can be arranged in a construction pit or a shaft, in particular asewer shaft. A ground drilling device can comprise a drive device ordrive which drives a drill string in a pulling and/or pushing manner. Itcan also be provided that the drive device drives the drill string in arotational manner. A rotary drive is understood to mean a rotation ofthe drill string—at least in portions—in one or both directions ofrotation about the longitudinal axis of the drill string. For example, aconstant left-hand or right-hand rotation can be impressed on the drillstring. In one embodiment, it is additionally or alternatively possiblethat the drill string can first be rotated by a predetermined angle inone direction of rotation and then rotated back by the same angle oranother angle, for example to allow for ground drilling in “paddle”mode.

The term “horizontal drilling” in the context of the descriptioncomprises in particular any type of, preferably horizontal, channelsexisting or to be created in a body, in particular underground channelsincluding underground bores, rock bores, or underground lines as well asunderground or above-ground pipelines and water channels that can becreated or dug in particular in portions that run horizontally using acorresponding ground drilling device.

In the context of the description, the terms “male connector” and“female connector” comprise a configuration as one element of a pair ofmechanical coupling elements, one of which (“male connector”) can beinserted at least partially into the other (“female connector”) in orderto form the plug connection.

If the description substantially focuses on the inner contour forforming the plug connection for the female connector, the outer contourof the female connector can in principle assume any shape. In apreferred embodiment, in cross section, the female connector has acircular outer contour. In a particularly preferred embodiment, theouter contour of the rod section is substantially the same outside theregion and in the region of the female connector and is particularlypreferably circular.

The term “cross section” in the context of the description comprises asection transverse to the longitudinal axis of the respective elementunder consideration in the region of the plug connection, i.e. for therod section or the drive element in the end-side region of the rodsection or the drive element, which is provided for the connection withthe element to be connected. The cross section is preferably viewed atan angle of 90° to the longitudinal axis. Slight deviations around theright angle to the longitudinal axis are possible.

In a preferred embodiment, the male connector is straight cylindricalwith a base area which has the cross section of the shape deviating froma circle. The male connector can thus have an outer side which extendsin a direction along the longitudinal axis of the rod section at asubstantially constant distance from the longitudinal axis. Thedelimitation of the male connector or the cross section runs along thelongitudinal axis of the rod section, at least in portions,substantially parallel to the longitudinal axis of the rod section, inparticular in an end region with which the male connector is inserted orplugged into the female connector. In a particularly preferredembodiment, the male connector has an outer contour at the end, withwhich the male connector is inserted into the female connector, whichouter contour runs parallel along the longitudinal axis of the rodsection. The outer contour of the male connector can be unchanged overthe length of the male connector.

In a preferred embodiment, the female connector is designed as a bodywith a corresponding cavity which has a delimitation, the distance ofwhich from the longitudinal axis in the direction along the longitudinalaxis of the rod section is substantially constant. The delimitation ofthe cavity of the female connector or the inner contour of the femaleconnector runs along the longitudinal axis of the rod section, at leastin portions, substantially parallel to the longitudinal axis of the rodsection, so that the surface delimiting the cavity can be straight inthe direction of the longitudinal axis of the rod section, i.e. itsubstantially does not enclose an angle with the longitudinal axis. In avery particularly preferred embodiment, the female connector has aninner contour at the end into which the male connector is inserted,which inner contour runs parallel along the longitudinal axis of the rodsection. The inner contour of the female connector can be unchanged overthe length of the female connector.

In a preferred embodiment, a rod section has a male connector at one endand a female connector at the other end. This allows for a simpleconnection to be established when the rod sections are in a specificorientation. In a particularly preferred embodiment, the inner contourand the outer contour of the female connector or the male connector arein a predetermined angular position to one another, so that therespective contours at the two ends of the rod section are flush withone another or aligned so that they can be plugged into one another.However, it can also be provided that the rod section has plug-inelements of the same shape at its end side, so that the rod section has,for example, a male connector at both ends or a female connector at bothends, which can have the corresponding contour described.

In the context of the description, a “shape deviating from a circle” isany geometric shape that does not have a circular shape. The shape,which is a shape deviating from a circle, thus not only includes pointsof a plane (the cross section that is being considered) which are at aconstant distance from a given point of this plane (center point). Thereis the possibility that the shape deviating from a circle has straightlines at least in portions. The shape can additionally or alternativelyhave curved or arched lines. As described below, the shape deviatingfrom a circle can also have a known, easily named configuration.

In a preferred embodiment, the shape deviating from a circle is an ovalshape, in particular a round convex figure, wherein the figure can be anellipse as a special case. In a particularly preferred embodiment, theshape deviating from a circle is an elliptical shape. In the context ofthe description, an ellipse is understood to mean a closed oval curvethat can be represented as a conic section. Usually, an ellipse is ashape with points in which the sum of the distances between a point andtwo predetermined points, the so-called focal points, is the same forall points. In the case of an ellipse, the straight line through thefocal points of the ellipse is usually designated as the major axis andthe straight line orthogonal thereto through the center of the ellipseis designated as the minor axis.

It can be provided that the, in particular oval, shape, which isdesigned in particular as an ellipse, is configured in such a way thatthe shape has no symmetry, whereby it can be achieved that the maleconnector and female connector can only be plugged together in anangular position to one another

In a preferred embodiment, the male connector or the female connectorhas an opening oriented transversely to the longitudinal axis of the rodsection for inserting a bolt which can be detachably connected to themale connector or the female connector, so that the oval shape is brokenthrough. This makes it possible to lock rod sections inserted into oneanother, in particular in the longitudinal direction of the rodsections. It can be achieved that a bolt, which is arranged transverselyto the longitudinal axis of the rod sections, can transmit thrust and/ortensile forces. By means of the opening and the inserted bolt, a simplepossibility can be selected by means of which thrust and/or tensileforces can be transmitted. It can be provided that only the tensileforces are transmitted through the bolt, whereby a simple element can beselected which is arranged as a securing element in a recess or theopening in the male connector or the female connector. It can beprovided that a thrust force is transmitted by means of abutting contactsurfaces from two adjacent rod sections in the drill string, so thatwhen the plug connection is formed, the mutually adjacent contactsurfaces of the adjacent rod sections are arranged for directtransmission of the thrust force. In particular, contact surfaces forthe transmission of thrust forces can be designed as shoulders or as anend region of each rod section, for example a contact surface can be ashoulder in the foot region of the male connector and a correspondingcontact surface can be the end region or head region of a femaleconnector.

In a preferred embodiment, the securing element or the bolt isconfigured to be reusable. In particular, the securing element is notnecessarily reshaped to form the securing means. The securing element orthe bolt can be made solid. The bolt can have a latching groove which,in particular in the middle, can be formed between the ends of the bolt.The latching groove can be formed on the entire circumference of thesecuring element or bolt, so that no preferred angular position has tobe maintained in which the securing element or the bolt has to beinserted. The securing element or the bolt preferably has a circularcross section; bolts or securing elements of this type can be easilyplanned and manufactured and the application does not require anyincreased requirements.

In order to apply a thrust or tensile force from a drive to the drillstring, the rod section can have at least one recess or groove, whichpreferably extends on the outside in portions or completely along anouter circumference. An element of the drive, for example in the form ofa (locking) pawl, can engage in the recess or groove and exert a thrustor tensile force. More than one recess or groove can be provided on arod section, in particular two or more recesses or grooves can beprovided, which can be at a distance from one another in thelongitudinal direction of the rod section.

In a particularly preferred embodiment, the openings are provided on themale connector and the female connector, which can be arranged such thatafter the plug connection of two adjacent rod sections has been formed,the openings are arranged in relation to one another in such a way thatthe opening on the male connector and the opening on the femaleconnector are flush with one another. The bolt can then be inserted intothe flush opening of the male connector and female connector.

In a preferred embodiment, the opening on the male connector is athrough opening. In a preferred embodiment, the opening on the femaleconnector is a through opening. The term “through opening” correspondsto an opening which penetrates each connecting element completelytransversely to the longitudinal direction of the connecting element. Inparticular for the through opening on the female connector, this canmean that two through openings, which can extend between the innercontour and the outer contour of the female connector, can be providedin the edge that can form the cavity of the female connector, whichthrough openings are on a straight line or can be formed along astraight line; the two through openings of the female connector can thusform an entire through opening. If the male connector with its throughopening is inserted into the female connector with its through opening,an entire through opening can be formed in that the through openings ofthe male connector and the female connector are flush and lie on astraight line into which through opening the securing element or thebolt can be inserted.

The openings in the connecting elements can in particular have acircular cross section. Such a shape of the opening is both easy to planand to produce. The assembly for the production of the securing means,i.e. an insertion of the bolt or securing element, can be done easily.

The openings can be formed in a solid portion of the rod section itself.The openings can be fixed or immovable in the rod section. Inparticular, the openings can be formed in the solid region of the rodsection. In particular, the openings can be formed in the body of therod section itself.

In a particularly preferred embodiment, the length of the bolt isadapted to the outside diameter of the female connector, so that thelength of the bolt substantially corresponds to the outside diameter ofthe female connector. With regard to the length of the bolt, it can beprovided that the bolt has a length which corresponds to the distancebetween the two secants for openings on the female connector, whichopenings are opposite one another. The length of the bolt can also be(slightly) less than the distance between the secants of the openings inthe female connector.

In a preferred embodiment, a line intersects the opening which enclosesan angle of less than 30° with the axis of symmetry of the inner contouror the outer contour or with an axis running perpendicular to the axisof symmetry of the inner contour or the outer contour. In this way, animproved connection in terms of the transmission of the tensile and/orcompressive forces can be achieved. The closer the line of the axis ofsymmetry approaches the inner contour or the outer contour or an axisrunning perpendicular to the axis of symmetry of the inner contour orouter contour, an improved transmission of the forces can be achieved.In a particularly preferred embodiment, the angle under considerationbetween the line that intersects the opening and the axis of symmetry orthe axis perpendicular to the axis of symmetry is less than 25°,preferably <20°, more preferably <15°, more preferably <10°, morepreferably <5°. In a particularly preferred embodiment, the line thatintersects the opening is substantially congruent with the axis ofsymmetry of the inner contour or the outer contour or is substantiallycongruent with an axis running perpendicular to the axis of symmetry ofthe inner contour or the outer contour.

In a preferred embodiment, the line which intersects the opening extendsalong a major or minor axis for an inner contour or outer contourdesigned as an ellipse, the minor axis being preferred. As a result, thepressing and cross-sectional surfaces and thus the strength of thefemale connector, male connector, and bolt can be selected to be almostthe same, whereby preferably almost the same material can be present forthe rod section and the bolt. An optimized transmission of tensileand/or compressive forces is possible.

In a preferred embodiment, the opening is part of a through hole whichextends completely through the male connector or the female connector.In this way, it can be achieved that the thrust and/or pressure forcescan be transmitted symmetrically. The entire diameter of the maleconnector or female connector can be used to transmit the thrust and/orpressure forces. In particular for the female connector, a through holecan be a hole that completely traverses the female connector, so that athrough hole is present in the contour at two opposite points in thefemale connector.

In a preferred embodiment, the opening and/or the through hole isconfigured to be threadless. This allows for simplified handling of therod sections to be achieved. A tool, in particular for a screwconnection, for forming the connection between two adjacent rodsections, in particular for transmitting a thrust and/or compressiveforce, can be dispensed with. If the focus is on the fact that theopening or the through hole can be threadless, a threadless design ofthe opening or through hole can also include a threadless configurationof the bolt in a rod section system.

In a preferred embodiment, a latching element for engaging the bolt isarranged in the male connector, the longitudinal extent of the latchingelement enclosing an angle of 0° to 45° with the longitudinal axis ofthe rod section. In this way, an improved securing of a bolt can beachieved. A loss protection for the bolt can be created, so to speak,which simplifies handling. In particular in conjunction with theconfiguration that the opening can be threadless, both improved safetyand improved handling are achieved. A latching element, in particularacted upon by a spring, which can engage in an outer structure of thebolt when it is inserted, can fix the position of the bolt in thethrough hole or through holes. The securing or latching can be canceledby applying a compressive force, in particular in the longitudinaldirection of the bolt, so that the bolt can also be easily removed fromthe opening and the rod sections can be detached from one another again.By means of the arrangement of the latching element opposite thelongitudinal axis of the rod section, a good latching of the bolt ispossible. Preferably, the longitudinal extent of the latching elementwith the longitudinal axis of the rod section can be an angle of 0° to35°, more preferably an angle of 0° to 25°, more preferably an angle of0° to 15°, more preferably an angle of 0° to 10°, more preferably anangle of 0° to 5°, more preferably an angle of 0°.

In order to bring the latching element into engagement on the bolt, thebolt can preferably have a groove which can be formed on the bolt overits entire circumference. The latching element can in particular beadapted to the groove; the tip of the latching element which comes intoengagement with the groove is very particularly preferably adapted tothe groove. For a low-wear configuration, the latching element can havea rounded, in particular spherical, segment-shaped tip.

In a preferred embodiment, at least one marking is provided on the rodsection on an outwardly directed surface, which is in a predeterminedangular relationship to the angular position of the shape. In thecontext of the description, an outward-facing surface is a surface thatis visible from the outside. Among other things, a simple assignment canbe made as to how rod sections must be rotationally aligned in order tobe able to be plugged into one another. The rotational alignment of therod section in relation to its longitudinal axis can be recognized. Theangular position of the shape can also be recognized from a direction inwhich the observer is not in an extension of the longitudinal axis ofthe rod section. It is possible that the marking is arranged on asurface which has a surface normal that runs transversely to thelongitudinal axis of the rod section or has a surface normal thatincludes a sufficiently large angle with the direction that runstransversely to the longitudinal axis of the rod section, e.g. greaterthan 10°. Even in the case of non-symmetrical shapes, quick alignment toform the plug connection is possible. In the case of a symmetrical shapeof the inner or outer contour, it is possible by means of the marking todistinguish whether the ground drilling rod has rotated through an angleof symmetry. For example, in the case of a shape configured as anellipse, the marking can be used to determine whether the rod section orthe ground drilling rod has rotated, in particular, by 180°. The 12o'clock position of the drill string can be tracked or set by means ofthe marking. By means of the rotation of the drill string, for example,conclusions about the angular position of the drill head can be made.

The invention also provides a drive element for driving a grounddrilling rod into the ground. The drive element is configured to bebrought into engagement with a rod section. The drive element thatengages with the rod section is configured (a) as a male connector or(b) as a female connector. In cross section, the outer contour or theinner contour has a shape deviating from a circle. In cooperation with arod section, in particular the one described above, a drill string canbe introduced into the ground, which can be better handled and/orconstructed in a simpler manner.

In a preferred embodiment, the male connector or the female connectorhas an opening oriented transversely to the longitudinal axis of the rodsection for inserting a bolt which can be detachably connected to themale connector or the female connector, so that the oval shape is brokenthrough. This allows tensile and/or compressive forces to betransmitted. A bolt provides the possibility of a simple configurationand can, for example, be replaced inexpensively and easily in the eventof wear.

The invention also provides a rod section system which comprises two ormore rod sections which are configured in accordance with the presentdescription. The rod section system also has a bolt that has acircumferential groove. The inner contour of the female connector of arod section is adapted to the outer contour of the male connector of afurther rod section in such a way that a form-fitting plug connectioncan be achieved. The shape and size of the inner contour and the outercontour are such that the male connector and the female connector caneasily be plugged into one another and play—with a tolerance-relateddeviation—is prevented as far as possible.

For easy handling, the rod section system has a plurality of rodsections, i.e. two, three or more, configured identically with regard tothe respective ends as male connector or female connector.

The invention further provides a ground drilling device which has adrive element as described.

Numbers in the context of the description are specifications that can besubject to a tolerance of +/−10%, so that the numbers not only denoteone value, but also describe a range of values, in particular to takeaccount of tolerance ranges that may be production-related.

The statements on the individual aspects of the invention, as they aredescribed in relation to the rod section, the drive element, the rodsection system, and the ground drilling device, are to be understood asmutually complementary statements. Statements on one aspect also applyto the statements on one of the other aspects.

Like the following description of embodiments, the above statements donot constitute a waiver of specific embodiments or features.

The invention is explained in more detail below with reference to anembodiment shown in the drawings, in which:

FIG. 1 is a side view in a partially sectioned illustration of a portionof a ground drilling device with a drill string having rod sections;

FIG. 2 is an isometric view of an enlarged view of two rod sectionswhich can be plugged into one another with a female connector and a maleconnector;

FIG. 3 is an enlarged illustration of a connection of two rod sectionsin a sectional illustration; and

FIG. 4 is a section transverse to the line A-A from FIG. 3 in the regionof the male connector, female connector, and bolt.

FIG. 1 shows, in a side view, schematically in a partially sectionedillustration, a section of a ground drilling device 2 which is insertedin a construction pit 3. By means of a drive, the ground drilling device2 can move a ground drilling rod, which has rod sections 5 and a drillhead 6, which is followed by a transmitter receptacle 7, into the ground8 in a pushing or pulling manner.

The movement is carried out by two hydraulic cylinders 1 of the drive,to which a pawl 10 is fastened, which can engage the rod sections 5 viacircumferential grooves 9 of the rod sections 5 in order to push theground drilling rod into the ground 8. The pawl 10 is connected tocylinder tubes 11 of the hydraulic cylinders 1. The pawl 10 pushesitself out of a groove 9 during the retraction (idle stroke) of thehydraulic cylinder 1 and, when it reaches a further groove 9, falls intothis groove, so that the hydraulic cylinder 1 can push the grounddrilling rod having the drill head 6, the transmitter receptacle 7, andthe rod sections 5 further in a next working stroke.

The ground drilling device can move the ground drilling rod in theground by pulling or pushing, and in the embodiment shown in FIG. 1, thehydraulic cylinders 1 can be rotated together with the pawl 10 in theireffective direction.

FIG. 2 shows, in an isometric illustration, two rod sections 5 connectedto one another via a plug connection 4 to form part of a ground drillingrod. The rod section 5 has two grooves 9 which are at a distance fromone another in the longitudinal direction and in which the pawl 10 canengage. FIG. 2 shows a male connector 12 at one end (right) and a femaleconnector 14 at the other end (left) for the rod section 5. In the leftedge region of FIG. 2, it can be seen that a further rod section 5, ofwhich only one end is shown, is inserted with its male connector 12 intothe female connector 14. The region of the plug connection 4 is providedwith a circle marked X.

FIG. 3 shows a section in the region X of the plug connection 4 of FIG.2. The male connector 12, which has an elliptical outer contour 25 incross section and is arranged at one end of the rod section 5, is pushedinto an elliptical inner contour 13 of the female connector 14 of afurther rod section 5.

An opening 28 and an opening 29, which are part of a through hole 17,are provided on the male connector 12. Furthermore, an opening 26 and anopening 27, which are part of a through hole 18, are provided on thefemale connector 14. When forming the plug connection of the femaleconnector 14 and the male connector 12, the through holes 17, 18 arecongruent and a bolt 16 can be inserted into the openings (26, 27, 28,29) of the through holes 17, 18.

A securing of the bolt 16 or a slipping of the bolt 16 out of thethrough holes 17, 18 is achieved by means of a spring-loaded latchingelement 15 which is configured as a pressure piece. The latching element15 is screwed into a sleeve having an external thread in the front endof the male connector 12. The latching element 15 engages with one end19, which is configured spherically in the illustrated embodiment, intoa circumferential groove 20 of the bolt 16.

To separate the rod sections 5, which are connected by means of the plugconnection 4 and the bolt 16, the bolt 16 can easily be pushed outcounter to the latching action of the latching element 15, in this casein the illustrated embodiment the spring force of the latching element15, which spring force acts on the spherical end 19 of the latchingelement 15.

FIG. 4 shows, in a section A-A from FIG. 3, the arrangement of the bolt16 in the direction of the minor axis X-X of the elliptical maleconnector 12 of the rod section 5. As a result of this arrangement andthe configuration (extension of the elliptical shape in the direction ofthe major and minor axes), the pressing surfaces 21, but also thecross-sectional surfaces of the male connector 12, female connector 14,and bolt 16 are almost identical.

In FIG. 2, a marking “12,” which is provided with the reference sign 22,can be seen on the outside of the female connector 14 on the end-sidecircumference. The marking 22 is in a predetermined angular relationshipto the shape of the inner contour 13 of the female connector 14. Themarking 22 is arranged on the outer circumference at the point of thefemale connector 14 at which the minor axis of the elliptical shape ofthe inner contour 13 intersects the outer circumference. The marking 22indicates how the rod section 5 is aligned in a rotational manner withrespect to its longitudinal axis.

1. Rod section (5) of a ground drilling rod, wherein the rod section (5)is configured at the end side to form at least one plug connection (4)and has at one end (a) a male connector (12) with an outer contour (25)or (b) a female connector (14) with an inner contour (13), characterizedin that, in cross section, the outer contour (25) or the inner contour(13) has a shape deviating from a circle.
 2. Rod section (5) accordingto claim 1, characterized in that the shape deviating from a circle isan oval shape, in particular an elliptical shape.
 3. Rod section (5)according to either claim 1 or claim 2, characterized in that the shapeof the outer contour (25) or the inner contour (13) is asymmetrical incross section.
 4. Rod section (5) according to any of claims 1 to 3,characterized in that the male connector (12) or the female connector(14) has an opening oriented transversely to the longitudinal axis ofthe rod section (5) for inserting a bolt (16) which can be detachablyconnected to the male connector (12) or to the female connector (14), sothat the oval shape is broken through.
 5. Rod section (5) according toclaim 4, characterized in that a line intersects the opening whichencloses an angle of less than 30° with an axis of symmetry of the innercontour (13) or the outer contour (25) or with an axis runningperpendicular to the axis of symmetry of the inner contour (13) or theouter contour (25).
 6. Rod section (5) according to claim 5,characterized in that the line extends along a minor axis of an innercontour (13) or outer contour (25) designed as an ellipse.
 7. Rodsection (5) according to any of claim 4 and 5 or 6, if dependent onclaim 4, characterized in that the opening (26, 27, 28, 29) is part of athrough hole (17, 18) which protrudes completely through the maleconnector (12) or the female connector (14).
 8. Rod section (5)according to any of claims 4 and 5 to 7, if dependent on claim 4,characterized in that the opening (26, 27, 28, 29) is configured to bethreadless.
 9. Rod section (5) according to any of claims 1 to 8,characterized in that a latching element (15) for engaging the bolt (16)is arranged in the male connector (12), the longitudinal extent of thelatching element (15) enclosing an angle of 0° to 45° with thelongitudinal axis of the rod section (5).
 10. Rod section (5) accordingto any of claims 1 to 9, characterized in that at least one marking (22)is provided on the rod section (5) on an outwardly directed surface,which is in a predetermined angular relationship to the angular positionof the shape of the inner contour (13) or the outer contour (25). 11.Drive element for driving a ground drilling rod into the ground, whichis configured to be brought into engagement with a rod section (5),wherein the drive element engaging with the rod section (5) isconfigured (a) as a male connector (12) or (b) as a female connector(14), characterized in that, in cross section, the outer contour (25) orthe inner contour (13) has a shape deviating from a circle.
 12. Rodsection system comprising two or more rod sections (5) according to anyof claims 1 to 10, characterized by a bolt (16) having a circumferentialgroove (20) for inserting into the opening (26, 27, 28, 29).
 13. Grounddrilling device having a drive element according to claim 11.